"Neurogenic rosacea is a syndrome that most of us recognize, but I wonder if it really is a form of rosacea. Patients are mainly female, average age 38 years, and they complain of frequent facial flushing and erythema. They also complain of burning and stinging of the facial skin, and they have a high frequency of neuropsychiatric symptoms such as complex regional pain syndrome and depression. Additionally, they're prone to neurovascular disorders such as headaches and Raynaud's phenomenon," Dr. Powell says.

Study authors suggest that neurogenic rosacea stems from the combination of a genetic predisposition and exogenous factors such as light, heat or microbes, he explains. "These factors initiate a neurovascular response, with vasodilatation, peptide release and central appreciation of pain. This is an interesting concept."

Rosacea's prevalence

Regarding rosacea's prevalence, "It seems to be at least as common as psoriasis," although statistics from different countries vary, Dr. Powell says. "In the United States, for example, the National Rosacea Society produced data suggesting there were 14 million patients. This was based on a survey of individuals who self-reported rosacea." However, he says, this methodology creates problems because many patients with facial redness assume they have rosacea when they might not.

Conversely, he says that European data reflect a prevalence rate of 0.1 to 1.7 percent. "These are mostly patients who are attending dermatology clinics."

In a study of Irish patients that Dr. Powell co-authored, "We found the prevalence of papulopustular rosacea to be exactly the same in indoor and outdoor workers: 2.7 percent (McAleer MA, Fitzpatrick P, Powell FC. J Am Acad Dermatol. 2010;63(1):33-39. Epub 2010 May 11). And we found no association between papulopustular rosacea and UV exposure," he says.

Additionally, unpublished data from this study showed that "patients who could be categorized as having erythematotelangiectatic rosacea were far more common among the outdoor workers," Dr. Powell says. "The changes that are categorized as erythematotelangiectatic rosacea are indeed significantly associated with photodamage. That raises the question, are papulopustular rosacea and erythematotelangiectatic rosacea in fact different conditions? We need to consider whether erythematotelangiectatic rosacea is in fact a form of heliodermatitis or actinic-induced skin changes in sensitive phototypes." Histologic changes and other laboratory findings differ between these two types of rosacea, he notes, as do appropriate treatments.